The present invention relates generally to the field of exhaust headers. More specifically, the present invention relates to an exhaust header system for interconnection with a catalytic converter and accompanied by enhanced engine performance.
Automotive internal combustion engines utilize exhaust systems for directing burnt gases out of the engine cylinders and for dampening exhaust noises. Factory-installed exhaust systems typically include an exhaust manifold, a catalytic converter coupled to an outlet of the exhaust manifold, an exhaust pipe extending from the catalytic converter to the rear of the vehicle, a muffler coupled to the end of the exhaust pipe, and a tailpipe extending from the muffler to outside the vehicle. Exhaust manifolds formed of thick cast iron and high-restriction mufflers are installed at the factory to achieve substantial sound dampening. A problem encountered with these manifolds and mufflers is that they severely impair the flow of exhaust gases, which greatly reduces the power output of the engine. In addition, the weighty cast iron material further decreases performance and increases gas consumption.
To increase engine efficiency and performance, the exhaust system can be replaced with commercially available low-restriction manifolds and mufflers that more effectively exhaust burnt gases without significantly increasing the exhaust noise. Low-restriction manifolds, typically referred to as xe2x80x9cheadersxe2x80x9d, can have equal or unequal length, lightweight, large diameter tubes tuned to a predetermined resonant frequency that scavenge the burnt gases from the engine with a high amount of efficiency.
In general, a header includes a flange plate that bolts up to the exhaust ports of an internal combustion engine, primary tubes that extend from holes in the flange plate at the exhaust port locations, and a collector tube at which the primary tubes are brought together. The collector tube receives the exhaust gas from the primary tubes and directs it toward the exhaust pipe.
A variety of header designs have been developed. A common design is one in which four primary tubes extend from the flange and are brought together in an approximately square configuration at a collector tube. Alternatively, three primary tubes may be brought together in an approximately triangular configuration at the collector tube. The total cross-sectional area of the primary tubes is collected and reduced to the cross-section of the exhaust pipe. In other designs, pairs of primary pipes are brought together, then the combined primaries are brought together in a collector tube. In racecars, the primary tubes extending from the flanges may be brought outside the vehicle independently, functioning as individual exhaust pipes. Yet in other designs, primary tubes from opposite banks of a V-8 or V-6 engine may be brought together in a selected configuration.
Uniform flow and avoidance of turbulence in the primary tube, collector, and exhaust system are important in reducing back pressure and maximizing both power and fuel efficiency. The point where the primary tubes come together and enter the collector has been found to be a problem area in assuring smooth, non-turbulent exhaust gas flow through the collector. The cross-sectional area of the combined primary tube outlet ends transitions through the collector to the (generally smaller) exhaust pipe cross-section. The cross-sectional area that is formed between the bundled primary pipe ends, for example, the approximately square configuration of four primary pipes and the approximately triangular configuration of three primary pipes, is a major cause of turbulence.
Attempts have been made to smooth this transition by cutting back the adjacent surfaces of adjacent primary pipes, then welding them together to substantially eliminate the area between the pipe ends. This is difficult, expensive in design and manufacture, and with a number of complex welds may actually add to turbulence in this transition region. Another attempt at smoothing this transition is the inclusion of a transition piece within the collector that attempts to guide the exhaust gas so as to provide a smooth transition from the greater combined internal cross-section of the primary pipe ends to the lesser cross-section of the collector pipe end. Unfortunately, the inclusion of such a transition piece results in undesirable design and manufacturing complexity, hence undesirably high cost.
In addition to reducing back pressure and maximizing both power and fuel efficiency, uniform flow and avoidance of turbulence is also important for enhancing the life span of the pollution-controlling catalytic converter. That is, a turbulent flow of exhaust gas through the catalytic converter can result in the formation of local hot spots, which degrades the catalyst within the converter and consequently severely reduces the life expectancy of the catalytic converter.
Thus, what is needed is a header system that produces a uniform flow of exhaust gas from the primary tubes to the collector, thereby reducing back pressure, maximizing power and fuel efficiency, and extending the life span of the catalytic converter.
Accordingly, it is an advantage of the present invention that an exhaust header system for an internal combustion engine is provided.
It is another advantage of the present invention that a header system is provided that produces a uniform flow of exhaust gas from the primary tubes to reduce back pressure, and maximize horsepower and fuel efficiency.
Another advantage of the present invention is that a header system is provided that produces a uniform flow of exhaust gas that effectively extends the life span of the catalytic converter.
Yet another advantage of the present invention is that a header system is provided that is cost effective to manufacture and install.
The above and other advantages of the present invention are carried out in one form by an exhaust header system for an internal combustion engine. The exhaust header system includes primary tubes, each having inlet and outlet ends. The inlet ends are adapted to carry exhaust gas from exhaust ports of the internal combustion engine. A collector has a collector inlet for receiving the exhaust gas from the primary tubes and a collector outlet, the outlet ends of the primary tubes converging at the collector inlet. The collector inlet exhibits an ovular cross-section, and the collector outlet exhibits a circular cross-section.
The above and other advantages of the present invention are carried out in another form by an exhaust header system for an internal combustion engine. The exhaust header system includes primary tubes, each having inlet and outlet ends. The inlet ends are adapted to carry exhaust gas from exhaust ports of the internal combustion engine. A collector includes a collector inlet for receiving the exhaust gas from the primary tubes and a collector outlet. The collector inlet exhibits an ovular cross-section defined by a width and a height, the width being greater than the height. The outlet ends of the primary tubes are aligned along the width. The collector further includes a collector outlet exhibiting a circular cross-section, and an intermediate section juxtaposed between the collector inlet and the collector outlet. The intermediate section carries the exhaust gas from the collector inlet to the collector outlet, and exhibits a cross-section that transitions from the ovular cross-section to the circular cross-section proximate the collector outlet.